The visible light communications technology is a brand new wireless communications technology that emerges in recent years, in which a light source performs communication while emitting light, and therefore, the light source not only can implement a lighting function, but also can implement a communication function. Compared with a conventional radio-frequency communications technology and other wireless optical communications technologies, the visible light communications technology has advantages such as high transmit power, not occupying a radio spectrum, no electromagnetic interference, no electromagnetic radiation, and saving energy and resources. Therefore, the visible light communications technology has become increasingly important.
Currently, researches on applications of the visible light communications technology mainly focus on indoor transport devices and outdoor visible light intelligent transport devices. When a visible light intelligent transport device performs communication by using visible light, the communication relies on precision of a visible light receiver rather than human eyes to recognize a device in which a visible light transmitter nearby is located. Therefore, when used in a transport system, the transport device can effectively avoid a potential safety hazard. For example, under a hazy weather with a visibility of only 100 meters, a driver of a vehicle A cannot recognize, with naked eyes, a vehicle B located 500 meters ahead of the vehicle A. In this case, the driver of the vehicle A may recognize the vehicle B by using a transport device.
However, the foregoing method has the following disadvantages: When a transport device simultaneously receives multiple visible light signals, because interference occurs between the multiple visible light signals, the transport device cannot accurately receive the visible light signals. For example, there are three vehicles that are 500 meters away from the vehicle A in different directions: a vehicle B, a vehicle C, and a vehicle D, and the three vehicles each send a visible light signal to the vehicle A simultaneously. Because the three visible light signals interfere with each other, none of the visible light signals can be accurately received by the vehicle A.